Waveguide with a three dimensional lens

ABSTRACT

Optical transmission structures include a waveguide and an optical lens wherein the optical lens has a sufficiently large thickness to allow the formation of a curved front lens surface that collimates transmitted light rays so that they travel within a plane that is coplanar to a working surface. The present invention also relates to a technique for manufacturing the optical transmission structure, which involves the use of a photopolymer material. The optical transmission structure can be implemented in various systems such as a system for optical data input.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.10/862,007, filed Jun. 4, 2004, now U.S. Pat. No. 7,267,930 and entitled“Techniques for Manufacturing a Waveguide with a Three-DimensionalLens.”

This application is also related to U.S. patent application Ser. No.10/862,003, filed on Jun. 4, 2004 and entitled “Waveguide With aThree-Dimensional Lens,” the content of which is hereby incorporated byreference.

This application is also related to U.S. patent application Ser. No.10/861,251, filed on Jun. 4, 2004, entitled “Apparatus and Method for aMolded Waveguide for Use with Touch Screen Displays,” and to U.S. patentapplication Ser. No. 10/758,759, filed on Jan. 15, 2004, entitled“Hybrid Waveguide,” and to U.S. patent application Ser. No. 10/817,564,filed on Apr. 1, 2004, entitled “A Data Input Device Using A LightLamina Screen and an Optical Position Digitizer,” which claims priorityfrom U.S. Provisional Patent Application No. 60/461,045, filed on Apr.8, 2003, the contents of each of which are hereby incorporated byreference.

FIELD OF THE INVENTION

The present invention relates generally to optical transmission devices,and more specifically to techniques for manufacturing opticaltransmission devices.

BACKGROUND

User input devices for data processing systems can take many forms. Twotypes of relevance are touch screens and pen-based screens. With eithera touch screen or a pen-based screen, a user may input data by touchingthe display screen with either a finger or an input device such as astylus or pen.

One conventional approach to providing a touch or pen-based input systemis to overlay a resistive or capacitive film over the display screen.This approach has a number of problems. Foremost, the film causes thedisplay to appear dim and obscures viewing of the underlying display. Tocompensate, the intensity of the display screen is often increased.

However, in the case of most portable devices, such as cell phones,personal digital assistants, and laptop computers, high intensityscreens are usually not provided. If they were available, the addedintensity would require additional power, reducing the life of thebattery of the device before recharge. The films are also easilydamaged. In addition, the cost of the film scales dramatically with thesize of the screen. With large screens, the cost is therefore typicallyprohibitive.

Another approach to providing touch or pen-based input systems is to usean array of source Light Emitting Diodes (LEDs) along two adjacent X-Ysides of an input display and a reciprocal array of correspondingphotodiodes along the opposite two adjacent X-Y sides of the inputdisplay. Each LED generates a light beam directed to the reciprocalphotodiode. When the user touches the display, with either a finger orpen, the interruptions in the light beams are detected by thecorresponding X and Y photodiodes on the opposite side of the display.The data input is thus determined by calculating the coordinates of theinterruption of the light beams as detected by the X and Y photodiodes.This type of data input display, however, also has a number of problems.A large number of LEDs and photodiodes are required for a typical datainput display. The position of the LEDs and the reciprocal photodiodesalso need to be aligned. The relatively large number of LEDs andphotodiodes, and the need for precise alignment, make such displayscomplex, expensive, and difficult to manufacture.

In view of the foregoing, there are continuing efforts to provideimproved data entry apparatus and methods having a continuous sheet or“lamina” of light provided in the free space adjacent a touch screen andto an optical position digitizer that detects data entries bydetermining the location of “shadows” in the lamina caused by an inputdevice, such as a finger or a stylus, interrupting the lamina whencontacting the screen.

BRIEF SUMMARY OF THE INVENTION

The present invention is directed to optical transmission techniques forthe efficient transmission of light rays within a desired plane that isabove a working surface. The techniques specifically relate to anoptical transmission structure that includes a waveguide and an opticallens. The optical lens is formed on the working surface and has asufficiently large thickness to allow the formation of a curved frontlens surface that collimates transmitted light rays so that they travelwithin a plane that is coplanar to the working surface. The presentinvention also relates to a technique for manufacturing the opticaltransmission structure, which involves the use of a photopolymermaterial. The optical transmission structure can be implemented invarious systems such as a system for optical data input.

As a method, one embodiment of the present invention includes at leastapplying a layer of photopolymer material onto a support substrate,providing a patterned grayscale mask that allows a certain pattern oflight to pass through the mask at varying intensities, exposing thelayer of photopolymer material to light that is directed through thegrayscale mask such that selected portions of the photopolymer materialare exposed to varying intensities of light, developing the layer ofphotopolymer material with a developer solution to remove portions ofthe layer of photopolymer material such that the remaining portion ofthe photopolymer material forms a waveguide that is integrated with anoptical lens, and rinsing the layer of photopolymer material to washaway the removed portions of the photopolymer material. In analternative embodiment, the method also includes forming the opticallens such that the optical lens has an in-plane collimating lens curvethat has an outline that is substantially defined within at least aplane that is perpendicular to a top surface of the support substrate,wherein light rays transmitted from the waveguide are collimated by theoptical lens so that the light rays are emitted through the in-planecollimating lens curve in a plane that is substantially coplanar to thetop surface of the support substrate. In another alternative embodimentof the method, the invention further includes forming the optical lenssuch that the optical lens has a directionally collimating lens curvethat has an outline that is substantially defined within at least aplane that is coplanar with the top surface of the support surface,wherein the light rays transmitted from the waveguide are collimatedsuch that substantially all of the light rays emitted through thedirectionally collimating lens curve are parallel to each other andtravel in a single direction.

In another embodiment of the invention, the method includes at leastapplying a layer of photopolymer material onto a support substrate,exposing the layer of photopolymer material to light that is directedthrough a patterned grayscale mask that allows a pattern of light topass through the mask at varying intensities such that selected portionsof the photopolymer material are exposed, developing the layer ofphotopolymer material with a developer solution to remove portions ofthe layer of photopolymer material such that the remaining portion ofthe photopolymer material forms a waveguide that is integrated with anoptical lens wherein the optical lens has a height that is larger than aheight of the waveguide and the optical lens has an inclined and curvedfront lens surface, and rinsing the layer of photopolymer material towash away the removed portions of the photopolymer material.

In another embodiment of the invention, the method includes at leastapplying a layer of photopolymer material onto a support substrate,exposing the layer of photopolymer material to light that is directedthrough a patterned grayscale mask that allows a certain pattern oflight to pass through the mask at varying intensities such that selectedportions of the photopolymer material are exposed to varying intensitiesof light, developing the layer of photopolymer material with a developersolution to remove portions of the layer of photopolymer material suchthat the remaining portion of the photopolymer material forms awaveguide that is integrated with an optical lens, wherein the opticallens has a front lens surface having a curvature that is defined withinthree dimensions, wherein light rays transmitted from the waveguide arecollimated by the optical lens so that the light rays are emittedthrough the front lens surface in a plane that is substantially coplanarto a top surface of the support substrate, and rinsing the layer ofphotopolymer material to wash away the removed portions of thephotopolymer material.

Another aspect of the invention is a system for manufacturing an opticalstructure that includes at least a support substrate having a topsurface, a layer of photopolymer material this applied to the topsurface of the support substrate, a light source that emits light, and apatterned grayscale mask having a grayscale pattern that allows adesired pattern of light from the light source to shine onto the layerof photopolymer material, the grayscale pattern also allowing light topass through the grayscale mask at different intensity levels, wherein awaveguide with an integrated optical lens can be formed in thephotopolymer material layer through a photolithography process.

These and other features and advantages of the present invention will bepresented in more detail in the following specification of the inventionand the accompanying figures, which illustrate by way of example theprinciples of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention, together with further advantages thereof, may best beunderstood by reference to the following description taken inconjunction with the accompanying drawings in which:

FIG. 1 illustrates a touch screen display system according to oneembodiment of the present invention.

FIGS. 2 and 3 illustrate a top plan and a side plan view, respectively,of an optical transmission structure according to one embodiment of thepresent invention.

FIGS. 4 and 5 illustrate a top and a side plan view, respectively, of anoptical 10 transmission structure according to an alternative embodimentof the present invention.

FIG. 6 illustrates a flow diagram that describes a method formanufacturing an optical structure according to one implementation ofthe invention.

FIGS. 7 and 8 illustrate a top plan and a side plan view, respectively,of a layer of photopolymer material that has been applied to a supportsubstrate wherein the photopolymer 15 material layer will be processedaccording to one embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will now be described in detail with reference toa few preferred embodiments thereof as illustrated in the accompanyingdrawings. In the following description, numerous specific details areset forth in order to provide a thorough understanding of the presentinvention. It will be apparent, however, to one skilled in the art, thatthe present invention may be practiced without some or all of thesespecific details. In other instances, well known operations have notbeen described in detail so not to unnecessarily obscure the presentinvention.

The present invention pertains to optical transmission techniques forthe efficient transmission of light rays within a desired plane that isabove a working surface. The techniques specifically relate to anoptical transmission structure that includes a waveguide and an opticallens. The optical lens is formed on the working surface and has asufficiently large thickness to allow the formation of a curved frontlens surface that collimates transmitted light rays so that they travelwithin a plane that is coplanar to the working surface. The optical lensshape efficiently collimates the light rays without the need foradditional collimating lenses and the manufacturing processes necessaryto incorporate such additional lenses. The present invention alsorelates to a technique for manufacturing the optical transmissionstructure, which involves the use of a photopolymer material. Theoptical transmission structure can be implemented in various systemssuch as a system for optical data input.

The present description will first describe an optical data input systemthat can utilize an optical transmission structure of the presentinvention. Then the description will go into detail regarding theoptical transmission structure and a method for making the opticaltransmission structure. It is noted that the optical transmissionstructure of the present invention can be used to transmit and/orreceive light signals even though the term “transmission” might lead oneto think that the structure can only be used for transmitting signals.Therefore, the term “transmission” does not functionally limit theoptical structure to the transmitting of signals.

Referring to FIG. 1, a touch screen display system according to oneembodiment of the present invention is shown. The touch screen displaysystem 10 includes a continuous plane or “lamina” 12 of light generatedin the free space adjacent to or just above a display screen 14. Thelamina 12 is generated by an X-axis input light source 16 and a Y-axisinput light source 18, each configured to propagate light across thefree space immediately above the surface of the screen 14 in the X and Ydirections respectively. The free space is generally parallel to thesurface of the screen 14 and is positioned just in front of the screen14. The lamina 12 is thus interrupted when an input device (not shown),such as a user's finger or a hand-held stylus or pen, is used to touchthe screen 14 during a data entry operation. An X-axis light receivingarray 20 and a Y-axis light-receiving array 22 are positioned on the twoopposing sides of the screen 14 opposite the X-axis and Y-axis lightsources 16 and 18 respectively. The light receiving arrays 20 and 22detect the X-axis and Y-axis coordinates of any interrupt or “shadow” inthe lamina 12, caused by an input device breaking the lamina 12 in thefree space above the screen 14 during a data entry operation. Aprocessor 24, coupled to the X-axis and Y-axis arrays 20 and 22, is usedto calculate the X-axis and Y-axis coordinates of the interrupt.Together, the X and Y-axis arrays 20 and 22 and the processor 24 providean optical position detection device for detecting the position ofinterrupts in the lamina 12. Based on the coordinates of the interrupt,a data entry on the screen 14 can be determined.

The light lamina 12 is substantially of uniform intensity according toone embodiment of the invention. The required dynamic range of thephotosensitive circuitry in the receiving X-axis and Y-axis arrays 20and 22 is therefore minimized and high interpolation accuracy ismaintained. In an alternative embodiment, however, a non-uniform lamina12 may be used. In this circumstance, the lowest intensity area of thelamina 12 should be higher than the light activation threshold of thelight detecting elements used by the X-axis and Y-axis arrays 20 and 22.

The display screen 14 can be any type of data display according tovarious embodiments of the invention. For example, the screen 14 can bea display for a personal computer, workstation, server, mobile computer,laptop computer, a point of sale terminal, personal digital assistance(PDA), cell phone, any combination thereof, or any type of device thatreceives and processes data entries.

The X and Y input light sources 16 and 18 are each a source ofcollimated light beams according to one embodiment of the invention. Thecollimated light may be generated in any of a number of different ways.For example, from a single light source mounted at the focal point of acollimating lens. Alternatively, the collimated light beams may begenerated from a plurality of point light sources and collimated lensesrespectively. In yet another embodiment, the X and Y input light sources16 and 18 can be made from a fluorescent light and a diffuser. The pointlight source or sources may be a Light Emitting Diode (LED) or aVertical Cavity Surface Emitting Laser (VCSEL).

In yet another embodiment, the light source may be a light transmitterwith spaced facets fed by a vertical laser.

The wavelength of the light generated by the X-axis and Y-axis lightsources 16 and 18 used to create the lamina 12 may also vary accordingto different embodiments of the invention. For example, the light may beof a wide-band having an extended wavelength spectrum range from 350nanometers to 1100 nanometers, such as white light from an incandescentsource. Alternatively, the input light can be of a narrow band having alimited spectrum ranging within 2 nanometers. The use of narrow bandlight enables the filtering of wide band ambient noise light. The use ofnarrow band light also enables the substantial matching of the lightwavelength to the response profile of the X-axis light-receiving array20 and the Y-axis light-receiving array 22. In yet another embodiment, ahomogeneous, single wavelength light, may be used. For example infraredor IR light, commonly used in wireless or remote data transfercommunications, may be used in this application.

The light sources, regardless of the type, may also be operated eithercontinuously or periodically, using on an on/off cycle. An on/off cycleconserves power, minimizes the heat generated by the source light, andpermits temporal filtering to reduce noise, such as lock in detection.During the off cycle, the X light receiving array 20 and a Y lightreceiving array 22 measure the passive or “dark” light (noise). The darklight measurement is then subtracted from the active light detectedduring the on cycle. The subtraction thus filters out DC backgroundcaused by the ambient light. During each off cycle, the passive lightmay also be calibrated, permitting the system to adjust to changingambient light patterns.

In yet another embodiment, the X-axis and Y-axis light sources 16 and 18may be cycled on and off intermittently. During alternate cycles, whenthe X-axis source 16 is on, the Y-axis source 18 is off, and vice versa.This arrangement requires less peak power since only one light source ison at a time, while still allowing subtraction filtering to occur duringeach X and Y on/off cycle respectively.

To reduce power consumption, a “sleep” mode may also be used for theX-axis and Y-axis light sources 16 and 18. If no data inputs are madefor a predetermined period of time, the intensity of the X-axis andY-axis light sources 16 and 18 may be dimmed. The rate at which shadowinterrupts are sampled is also done at a low rate, for example,approximately 5 times a second. When a shadow interrupt is detected, theintensity of the X-axis and Y-axis light sources 16 and 18 and thesampling rate are all increased to a normal operating mode. If no shadowinterrupts are detected after the predetermined period of time, X-axisand Y-axis light sources 16 and 18 are again dimmed and the samplingrate reduced.

The X-axis and Y-axis arrays 20 and 22 each include substrate waveguidearrays and photosensitive elements. The photosensitive elements areconfigured to convert light signals into electrical signals indicativeof the intensity of the received light. Specifically, each substrate hasa plurality of waveguides. Each waveguide has a free space end proximatethe lamina 12 and an output end proximate to a photosensitive element.The photosensitive elements are either affixed to or positioned adjacentthe output end of the waveguides respectively. For a detailedexplanation of the use and manufacture of waveguides, see U.S. Pat. No.5,914,709 by David Graham et al., the inventor of the presentapplication, and incorporated by reference herein for all purposes. Thephotosensitive elements can be implemented using a number of well-knownways, for example using Charge-Coupled Devices (CCD) or CMOS/photodiodearrays. Either type of imaging element can be implemented in many forms,including on a dedicated integrated circuit such as an applicationspecific integrated circuit, a programmable circuit, or any other typeof integrated or discrete circuit containing photosensitive areas orcomponents. Again, additional details on the various types ofphotosensitive elements that may be used with the present invention arediscussed in the aforementioned patent. Regardless of the type ofphotosensitive elements used, the output electrical signals indicativeof the received light intensity along the X and Y coordinates areprovided to the processor 24. The processor 24 determines the locationof any shadows in the lamina, caused by an interrupt in the lamina 12during an input operation, based on the electrical signals.

FIGS. 2 and 3 illustrate a top plan and a side plan view, respectively,of an optical transmission structure 100 according to one embodiment ofthe present invention. Optical transmission structure 100 includes awaveguide 102 and an optical lens 104. Optical transmission structure100 is formed upon a bottom cladding layer 120, which is formed upon asupport structure 106. A top cladding layer 122 covers the top surfaceof waveguide 102. The dashed directional lines of FIGS. 2 and 3generally illustrate the path of light rays that pass through opticalstructure 100. The directional arrows show the light rays as beingtransmitted out of optical structure 100, however, it should beunderstood that light rays can also be received into optical structure100 along substantially the same paths shown by the dashed lines.

Waveguide 102 and optical lens 104 can be formed of any suitablematerial for conveying light or light signals throughout its medium,such as a polymer based material, optical plastic, and epoxy. Waveguide102 and optical lens 104 can be integrally formed with each other,formed separately and then attached to each other, or even formed inproximate locations with respect to each other. As shown in FIGS. 2 and3, waveguide 102 and 104 are integrally formed with each other. Theintegrally formed waveguide 102 and optical lens 104 is more easilymanufactured since alignment issues between the two components areobviated. Typically waveguide 102 and optical lens 104 are formed of thesame material. However, in some embodiments where waveguide 102 andoptical lens 104 are formed separately, these two components can be madefrom different materials.

Top and bottom cladding layer 122 and 120, respectively, serve toimprove the optical transmission qualities of waveguide 102. Top andbottom cladding layers 122 and 120 are selected to have indexes ofrefraction that complement that of waveguide 102. The cladding layersalso serve to physically protect waveguide 102, which can be made of afragile material. Top cladding layer 122 covers waveguide 102 in FIG. 3.However, in alternative embodiments, top cladding layer 122 also coversback surface 110 of optical lens 104. Top cladding layer 122 should notcover the surfaces of optical lens 104 through which light rays travelin and out of. In some embodiments, no top cladding layer is applied tothe top surface of waveguide 102. In these embodiments, waveguide 102 isleft without physical protection and the ambient air acts as thecladding layer. The index of refraction for air can often be optimal forlight transmission purposes. Note that top cladding layer 122 is notshown in FIG. 2 in order to more clearly illustrate the structure ofwaveguide 102.

Bottom cladding layer 120 extends beneath waveguide 102 and optical lens104. In some embodiments, bottom cladding layer 120 is not utilized, assupport substrate 106 can act as a cladding layer. In these embodiments,support substrate 106 should be properly selected for its index ofrefraction. Waveguide 102 is an elongated structure for transmittinglight between two points. In the present invention, one end of waveguide102 is connected to an optical lens 104 and the opposite end isconnected to a light source or a light-detecting device. The lighttransmission capacity of waveguide 102 can be adjusted by varying thedimensions of the waveguide 102.

For example, the diameter or width and height of waveguide 102 can besized appropriately. The height or thickness, H_(w), waveguide 102 canbe seen in FIG. 3 and the width, W_(w), of waveguide 102 can be seen inFIG. 2. The cross-sectional shape of waveguide 102 can be rectangular orrounded.

Optical lens 104 has a height or thickness, HL that is larger thanH_(w). Optical lens 104 rises in height from its interface withwaveguide 102 to the apex 108 of HL of optical lens 104. Back surface110 defines the shape of optical lens 104 between waveguide 102 and apex108. In this embodiment, back surface 110 has a substantially flatsurface. The height of optical lens 104 allows a front surface ofoptical lens 104 to have a curvature that is defined in either two orthree dimensions. A two-dimensional curvature of optical lens 104 is acurve that has an outline that is defined within a single plane, forexample in the X-Y, X-Z, or Y-Z plane. In other words, the curve isdefined within two dimensions. A three-dimensional curvature is definedwithin three dimensions. For example, such a curve would have an outlineshape that is defined within each of two planes such as the X-Y and theX-Z planes. As will be described, the optical lens 104 of FIGS. 2 and 3has a three-dimensional curvature wherein the curvature has an outlineshape defined within the X-Y and the X-Z planes.

The front surface of optical lens 104 slopes downward from apex 108 tothe front edge of lens 104 that interfaces with support substrate 106.This slope can be seen in the side plan view of optical structure 100 ofFIG. 3. FIG. 3 also illustrates the cross-sectional view of opticalstructure 100 in the X-Z plane. The sloped surface is curved and formsthe in-plane collimating lens curve 112. In-plane collimating lens curve112 is formed throughout the front surface of optical lens 104 andcollimates exiting light rays such that they are substantially parallelwith the top surface of support substrate 106. The in-plane collimatinglens curve 112 directs the light rays across the support substraterather than allowing some of the light rays to shoot away from supportsubstrate 106.

The outline of the in-plane collimating lens curve 112 is defined withina plane that is perpendicular to the top surface of support substrate106 and which is aligned with the direction that a particular light raytravels. As such, the in-plane collimating lens curve 112 is visiblefrom the side-plan view of FIG. 3, which also represents the X-Z plane.FIG. 3 shows the in-plane collimating lens curve 112 for light rays thattravel along the longitudinal axis 116 of waveguide 102 as seen in thetop plan view of FIG. 2. The curvature of the in-plane collimating lenscurve 112 depends upon the height of optical lens 104 and the distanceof the front surface of optical lens 104 from waveguide 102. Thecurvature of the in-plane collimating lens curve also depends upon otherfactors such as the nature of the light rays and the index of refractionof the lens material and the surrounding environment. With respect todata input system 10 of FIG. 1, in-plane collimating lens curve 112 ofoptical lens 104 allows the input light sources 16 and 18 to moreefficiently form a lamina 12 of light because less light loss isexperienced. Advantageously, this reduces the power requirements neededto form lamina of light 12. Without the in-plane collimating lens curve112, light rays from optical structure 100 would diffract and a portionof the light rays would be directed away from support surface 106. Toaccomplish the same functions of the in-plane collimating lens curve112, an additional optical lens would need to be positioned in front ofoptical lens 104. This would be a more complicated optical system tomanufacture in terms of time, effort, and resources. For example, theprocess of aligning the additional lens with optical lens 104 would betime consuming and would be highly subject to alignment errors.

Notice that in-plane collimating lens curve 112 has a curve that forms aportion of a hemispherical arc. Therefore, optical lens 104 can be saidto form one-half of a full lens wherein the missing half would be themirror reflection of optical lens 104 along the x-axis. As will bedescribed below, the shape of optical lens 104 is more easilymanufactured than if optical lens 104 had a full lens shape. Also, the“half-lens” shape of optical lens 104 allows for easier integration andalignment with waveguide 102. Specifically, the “half-lens” shape ofoptical lens 104 makes a photolithographic manufacturing process idealfor manufacturing optical structure 100.

The in-plane collimating lens curve 112 as seen in the side plan view ofFIG. 3 is independent from the directionally collimating lens curve,which can be seen from the top plan view of optical lens of FIG. 2. Notethat FIG. 2 illustrates a view of optical structure 100 in the X-Yplane. The outline shape of directionally collimating lens curve 114 isdefined within a plane that is coplanar with the top surface of supportsubstrate 106. Directionally collimating lens curve 114 collimates theexiting light rays to travel parallel to each other and in a singledirection. Essentially, directionally collimating lens curve 114 allowsoptical lens 104 to create a uniform beam of light. With respect to datainput system 10 of FIG. 1, directionally collimating lens curve 114allows each optical structure 100 to form a uniform beam of light thattravels across display screen 14.

Optical lens 104 is shaped to allow light rays to travel between frontlens surface 112 and waveguide 102. To allow the maximum amount of lightfrom waveguide 102 to be collimated by front lens surface 112, backsurface 110 should have an angle of at least sin⁻¹ (√{square root over(n₁ ²−n₂ ²)}/n₃). Such an angle is referred to as the critical angle 118of optical lens 104 Note that n₁, is the index of refraction ofwaveguide 102, n₂ is the index of refraction of the top cladding layer120 or bottom cladding layer 122, whichever is larger, and n₃ is theindex of refraction of optical lens 104. Note that when optical lens 104and waveguide 102 are formed of the same materials, n1 and n3 will havethe same value. Note that the maximum amount of light that can becollimated by front lens surface 112 is inherently limited due to theshape of optical lens 104. Since optical lens 104 has a partial lensshape, wherein a full lens would have a shape that mirrors optical lens104 along the x-axis, approximately one-half of the light transmittedfrom waveguide 102 is lost. As such, optical structure 100 hasapproximately 3 dB light loss. In some embodiments, sacrificing somemore light loss, by allowing back surface 110 to have an angle less thanthe critical angle, to get an optical lens with a smaller HL issuitable. In an alternative embodiment, back surface 110 of optical lens104 can rise beyond a flat surface defined by the critical angle 118(see FIGS. 4 and 5). Such an embodiment is also effective since thematerial above the critical angle 118 does not affect the light raysthat travel through the rest of optical lens 104.

As seen from the top plan view of FIG. 2, optical lens 104 has a coneshape where the width, WL of optical lens 104 increases as optical lens104 extends away from waveguide 102. The cone shape of optical lens 104allows the light rays from waveguide 102 to expand throughout opticallens 104 until they are collimated into a uniform beam by directionallens curve 114. The cone-like proportions of optical lens 104 dependsupon the optical performance requirements of each optical structure 100.

In alternative embodiments, optical lens 104 can have various sizes andshapes. For example, optical lens 104 need not have a cone shape as seenfrom a top plan view as in FIG. 2. Also, optical lens 104 could have aflat front surface as seen from top plan view of FIG. 2 in situationswhere the light rays need not be emitted in a uniform beam of light. Inone embodiment, optical lens 104 can have a height, HL in the range of50 to 200 um and a length in the range of approximately 0.8 to 1.2 mm.Sometimes the size of optical lens 104 is constrained by the size of thesystem within which it is utilized, for example a display screen asshown in FIG. 1. Specific sizes of optical lens 104 are also determinedby relative indexes of refraction for the optical structure 100 and thesurrounding environment. For example, the type of cladding thatsurrounds the optical structure 100 is also a determinative of theoptical lens 104 dimensions.

Support structure 106 can be any surface across which light rays aremeant to be directed across for example, display screen 14 as shown inFIG. 1. Alternatively, support structure 106 can also be a structurethat is separate from a display screen. For example, support structurecan be a separate mounting surface that supports each optical structure100 which is then positioned proximate to a working surface such as adisplay screen. In these other embodiments, support structure can be alayer of plastic, epoxy, or a polymer. Support structure 106 can also bea cladding layer meant to protect waveguide 102 from physical damage andto increase the optical transmission efficiency of the waveguide 102.

In one embodiment, multiple optical structures 100 are formed in a rowso that multiple light beams are directed across a working surface, suchas a display screen 14 in FIG. 1. At the same time, another row ofoptical structures 100 are formed to receive each light beam. Two setsof such optical structures can then be formed so that light beams crossdisplay screen 14 along two axes, such as an X and Y-axes.

FIGS. 4 and 5 illustrate a top and a side plan view, respectively, of anoptical transmission structure 200 according to an alternativeembodiment of the present invention. Optical transmission structure 200includes a waveguide 202 and an optical lens 204. Optical transmissionstructure 200 is formed upon a support structure 206. The dasheddirectional lines of FIGS. 2 and 3 generally illustrate the path oflight rays that pass through optical structure 100. The directionalarrows show the light rays as being transmitted out of optical structure100, however, it should be understood that light rays can also bereceived into optical structure 100 along substantially the same pathsshown by the dashed lines.

Note that no top cladding layer is applied over the top of waveguide 202and optical lens 204. Also note that no bottom cladding layer supportsoptical structure 200. However, support substrate 206 can serve as abottom cladding layer by selecting the material of support substrate 206to have an appropriate index of refraction.

As described with respect to FIGS. 2 and 3, optical lens 104 also has anin-plane collimating lens curve 212 that can be seen in FIG. 5 and a.directional lens curve 214 that can be seen in FIG. 4. However, as canbe seen in FIG. 5, optical lens 204 has a back surface 210 that extendsbeyond the critical angle 118 as shown in FIG. 3. Back surface 210 has aheight, H_(L) that is substantially uniform until it quickly drops offto join with waveguide 202. Also, as can be seen from the top plan viewof FIG. 4, optical lens 204 has an extended portion 208 having a uniformwidth, W_(L). In some situations, the specific dimensions andproportions of optical lens 104 can be easily manufactured and can bemore easily integrated with another system.

FIG. 6 illustrates a flow diagram 300 that describes a method formanufacturing an optical structure according to one implementation ofthe invention. In some embodiments, the manufactured optical structurehas a lens surface that has a curvature defined in three-dimensions.FIGS. 7 and 8 will also be described along with FIG. 6 in order to morefully illustrate the operations of flow diagram 300. FIGS. 7 and 8illustrate a top plan and a side plan view of a layer of photopolymermaterial 400 that has been applied to a support substrate 402 whereinthe photopolymer material layer will be processed according to oneembodiment of the present invention.

Generally, flow diagram 300 describes manufacturing an optical structurethrough the use of photopolymers, grayscale masks, and photolithographictechniques. However, it should be understood that there are othertechniques for manufacturing the optical structure of the presentinvention. For example, micromolding techniques can be used to fabricatethe lens structures at desired sizes and scales. Also, the lensstructure can be fabricated of glass, plastics, ceramics, and othermaterials using three-dimensional grayscale photoresist structures,three-dimensional resist structures fabricated by “reflow” techniquesfollowed by a “dry” industrial etch process including reactive ionetching, ion milling, and other plasmabased combinations and methods.

Photopolymers are imaging compositions based on polymers, oligomers, ormonomers, which can be selectively polymerized and/or cross linked uponexposure to light radiation such as ultra-violet light. Photopolymersare leveraged industrially as patternable systems where light inducedchemical reactions in the polymer chemistry result in a differentialchange in solubility between regions exposed to light and regions notexposed to light (masked). Photopolymers can be made into differentforms including film/sheet, liquid, solution etc., which can be used inprinting plates, as photoresists, and in stereolithography and imaging.One conventional use of photopolymers is to form printing plates whereina photopolymer plate is exposed to a pattern of light to create aprinting plate. The plate is then used for ink printing. Photopolymersare widely used in the electronics and micro-device industries asphotoresists used to create intricate patterns in microscopic circuitson semiconductor chips, printed circuit boards, and other products.Photopolymers are also used as ultraviolet adhesives used to attachoptical fibers and for other industrial applications.

Photopolymer materials can be exposed to light that is directed througha patterned mask. Such patterned masks can be grayscale masks. Grayscalemasks have a designed pattern that in addition to allowing light to passthrough in a desired pattern, allows light to pass through the mask atvarying intensities. Grayscale masks can therefore allow a photopolymerlayer to be exposed to a pattern of light that has varying lightintensities. In this way, portions of a photopolymer layer can beremoved depending upon the level of light intensity received. This meansthat the depth of photopolymer material removal can be controlled. Forexample, photopolymer material can be removed from an entire section ora portion of photopolymer material can be removed to leave a remaininglayer of photopolymer material that has a varying thickness.Photopolymers can therefore be formed into specific structures withpredetermined dimensions in three dimensions. In alternative embodimentsof the invention, masks that either allow light to completely passthrough or completely block light can also be used.

Flow diagram 300 of FIG. 6 starts at block 302 where a layer ofphotopolymer material 400 is applied onto the top surface of a supportsubstrate 402. Note that the reference numbers mentioned in thedescription of flow diagram 300 reflect the reference numbers shown inFIGS. 6, 7 and 8. The layer of photopolymer material 400 typically has arelatively uniform thickness. Since some embodiments of themanufacturing process 300 will be used to make the optical structure asseen in FIGS. 2-5, the photopolymer layer 400 should have a thicknessthat is at least equal to the height, HL of the optical lens. Thephotopolymer material should be of a quality to that efficientlytransmits light. For instance, the photopolymer material can be of avery clear quality. The photopolymer material can be of positive ornegative tone for photolithography purposes.

Support substrate 402 has a top surface upon which photopolymer materiallayer 400 is applied. Support substrate 402 will typically be asubstrate that can be mounted within a photolithography system so thatthe layer of photopolymer material 400 can be processed. Supportsubstrate 402 can be formed of materials such as, but limited to,plastics, polymers, ceramics, semiconductors, metals, and glass. Supportsubstrate 402 can also be a cladding layer meant to surround a waveguidethat will be formed from the photopolymer material. Such a claddinglayer protects structures formed from the photopolymer layer 400 and itsinherent index of refraction facilitates the transmission of lightthrough the photopolymer material. At the end of the manufacturingprocess, support structure 402 and the structures formed from thephotopolymer material layer 400 can be transported and then attached toa device, such as an optical input device 10 as shown in FIG. 1.

In an alternative embodiment, a bottom cladding layer is applied to thesupport substrate 402, after which photopolymer material layer 400 isthen applied on top of the bottom cladding layer. In the embodimentshown and described in FIGS. 6-8, depending upon the material selection,support substrate 402 can serve as the bottom cladding layer. A bottomcladding layer can also be applied to the surface of support substrate206 through photolithographic techniques.

At block 304, the layer of photopolymer material 400 is exposed to apattern of light that is created with a patterned grayscale mask 404.This is performed by shining a light source through patterned grayscalemask 404, or by blocking light from passing through this mask. Grayscalemask 404 is patterned to create a waveguide and an optical lens withinphotopolymer material layer 400. The waveguide and the optical lens canbe integrally formed as shown in FIGS. 2-5. Using the same referencenumbers from FIGS. 2 and 3, the cross-hatched region in FIGS. 7 and 8represent the waveguide 102 and the optical lens 104 that will be formedwithin photopolymer material layer 400. In other words, thecross-hatched area represents the portion of the photopolymer layer 400that will remain after completing the photolithography process. The topplan view of FIG. 7 shows that grayscale mask 404 allows light to exposethe region of photopolymer material layer 400 outside of the waveguide102 and optical lens 104 and conversely protects the photopolymermaterial 400 that will form waveguide 102 and optical lens 104 fromexposure to light.

Light that shines through grayscale mask 404 is represented bydirectional and dashed lines 406 in FIG. 8. The grayscale nature of mask404 allows light to pass through at varying intensities and thereforeallows light to penetrate photopolymer material layer 400 to varyingdepths. The end point for each of lines 406 represents the depths towhich each light ray penetrates photopolymer material layer 400. Thematerial composition of photopolymer layer 400 is changed by the lightexposure only with respect to the depth of light penetration andresulting chemical changes in photopolymer system produced by thisexposure gradient. The light exposure gradient refers to the pattern oflight created by the grayscale mask wherein the light rays that passthrough the mask have varying intensities. In this way,three-dimensional (or “contoured”) structures, such as optical lens 104,can be formed from photopolymer material layer 400. Specifically, afront lens surface having an in-plane collimating lens curve 112 can beformed as seen in the side plan view of FIG. 8. As described above thein-plane collimating lens curve has an outline that is defined within aplane that is perpendicular to the top surface of support structure 106.Also, the front lens surface has a directionally collimating lens curve114 as seen in the top plan view of FIG. 7. As described above, thedirectionally collimating lens curve has an outline that is definedwithin a plane that is coplanar with the top surface of the supportstructure 106. Also, optical lens 104 has a back surface 110 that isinclined and extends from waveguide 102 to the top of optical lens 104.Grayscale mask 404 can be patterned so that back surface 110 can haveany shape so long as it at least rises above the critical angle 118 ofsin⁻¹(√{square root over (n₁ ²−n₂ ²)}/n₃) wherein n1 is the index ofrefraction of waveguide 102, n2 is the index of refraction of thesupport substrate 402, which acts as the bottom cladding layer, and n3is the index of refraction of optical lens 104.

In alternative implementations of block 304, photopolymer material layer400 can be exposed to various patterns of light through grayscale mask404 to form various structures within photopolymer material layer 400.For example, various three-dimensional or two-dimensional structures canbe formed. Specifically, optical lens 104 could have a lens surface thathas either one of an in-plane collimating or a directionally collimatingcurve. An optical lens 104 having only a directionally collimating lenscurve 114 can have a height that is the same as waveguide 102 such thatthe optical structure has a flat top surface.

Waveguide 102 can be formed to have a rectangular or a roundedcross-sectional shape. In one embodiment, waveguide 102 can be formed tohave a rectangular cross-sectional shape that has a height and width ofapproximately 8-10 microns each. The lengthwise dimension of waveguide102 can extend along a straight or curved path in order to connect to alight source or light detector.

The use of photopolymer material layer 400 is advantageous since opticallens 104 and waveguide 102 can be easily formed to be integral with eachother. This eliminates any arduous task of aligning a waveguide with anoptical lens. The ability to form an optical lens that has an in-planecollimating lens curve 112 also simplifies the manufacturing process ofcertain optical structures in that a separate lens is not needed toperform the function of the inplane collimating lens curve 112. Such aseparate lens would require additional resources for the lens itself andfor the positioning and alignment.

Identical optical lens structures can be created in photopolymers usingpositive-tone masks with negative-tone optical photopolymer, or by usingnegative-tone masks with positive-tone optical photopolymer.Positive-tone photopolymer material systems and negative-tonephotopolymer material systems can be used with gray scale maskingtechniques to create exposure gradients resulting in three-dimensionalpolymeric structures following development. Again, structures formed bythe photopolymer material form engineered structures such as thewaveguides and the optical lenses.

In FIGS. 7 and 8, the portion of photopolymer material layer 400 that isexposed to light can be removed during a subsequent developingprocess—positive tone. The length of each dashed line 406 of FIG. 8 canrepresent the energy vectors, or the amount of light energy, of eachlight ray that shines upon photopolymer material layer 400.

In alternative embodiments where photopolymer material layer is negativetone, the light causes the photopolymer material to cross-link intostronger structures than what are formed with positive-tone photopolymersystems. The unexposed areas of the photopolymer material will be washedaway. Wherein the length of each dashed line 406 of FIG. 8 can be viewedas proportional to the light energy of each light ray for a positivetone photopolymer material layer, the inverse amount of energyrepresented by each dashed line 406 is suitable for a negative tonephotopolymer material layer.

In some implementations of the manufacturing process 300, multipleoptical structures formed of both a waveguide 102 and an optical lens104 can be formed. The multiple optical structures can be formed so thatan array of light beams are directed out of the optical lenses 104. Suchan array of light beams can form a lamina of light 12 as shown in FIG.1.

In block 306, a developer solution is washed over photopolymer materiallayer 400 in order to develop the photopolymer material layer 400. Thedeveloper solution can be an organic solvent or an aqueous solution.Exemplary developer solutions include but are not limited toMethyl-Iso-Butyl-Ketone(MIBK), Tetra-Methyl-Ammonium-Hydroxide(TMAH),and Potassium Hydroxide (KOH). Dry development using plasma-basedprocessing is also possible. The developer solution removes regionsexposed to light at different rates than regions not exposed to light(differential solubility is induced by light induced chemical reactionsin photopolymers) resulting in useful patterns following developmentprocessing. The portions of photopolymer material 400 that were notexposed to light remain intact and form the desired structure, such aswaveguide 102 and optical lens 104.

In block 308, another aqueous solution, for example an organic solventis used to rinse away the developer solution and the dissolved portionsof photopolymer material layer 400.

Then in block 310, the remaining optical structure formed from thephotopolymer material layer 400 and support substrate 402 are putthrough a drying process. In this process, the rinsing aqueous solutionis dried off. The drying operation of block 310 can be performed invarious manners such as with heat, spinning, and/or air blowing.

The support substrate 402 and photopolymer material layer 400 can beformed at a size and shape that fits within a photolithography system,such as one suitable for semiconductor manufacturing. In one embodiment,support substrate 402 and photopolymer material layer 400 can be formedupon a wafer, such as a semiconductor wafer, that can be placed within aphotolithography system.

In some implementations of method 300, a top cladding layer can beapplied on top of waveguide 102 and optical lens 104.

While this invention has been described in terms of several preferredembodiments, there are alteration, permutations, and equivalents, whichfall within the scope of this invention. It should also be noted thatthere are many alternative ways of implementing the methods andapparatuses of the present invention. It is therefore intended that thefollowing appended claims be interpreted as including all suchalterations, permutations, and equivalents as fall within the truespirit and scope of the present invention.

1. An apparatus, comprising: a bottom cladding layer; a photopolymermaterial formed on the bottom cladding layer, the photopolymer materialbeing patterned to form a waveguide on the bottom cladding layer andhaving a first height with an integrated optical lens formed on thebottom cladding layer and having a second height, wherein the secondheight is greater than the first height; wherein the optical lens has adirectionally collimating lens curve that has an outline that issubstantially defined within at least a plane that is coplanar with thetop surface of the bottom cladding layer, wherein the light raystransmitted from the waveguide are collimated such that substantiallyall of the light rays emitted through the directionally collimating lenscurve are parallel to each other and travel in a single direction; and atop cladding layer formed on at least the waveguide.
 2. The apparatus ofclaim 1, further comprising a substrate, the bottom cladding layer beingformed on the substrate.
 3. The apparatus of claim 1, wherein theoptical lens has a thee-dimensionally contoured shape.
 4. The apparatusof claim 1, wherein the optical lens has an inclined back surface thathas a first edge that joins the waveguide and a second edge that extendsto the second height of the optical lens.
 5. The apparatus of claim 4,wherein the inclined back surface is substantially flat and is inclinedat an angle.
 6. The apparatus of claim 1, wherein the optical lens has awidth that expands as the optical lens extends away from the waveguide.7. An apparatus, comprising: a bottom cladding layer; a photopolymermaterial formed on the bottom cladding layer, the photopolymer materialbeing patterned to form a waveguide on the bottom cladding layer andhaving a first height and being patterned to form an optical lens on thebottom cladding layer such that the lens is integrally and continuouslyformed with the waveguide such that the lens includes a second heightthat is greater than the first height; and a top cladding layer formedon at least the waveguide.
 8. The apparatus of claim 7, wherein theoptical lens is a collimating lens.
 9. The apparatus of claim 8, whereinthe collimating lens has a curve that defines a front lens surface thatextends from the bottom cladding layer to the second height of theoptical lens.
 10. The apparatus of claim 7, wherein the waveguide andoptical lens formed on the bottom cladding layer are contiguously formedof a single photopolymer material arranged on the bottom cladding suchlight passing through the integrated waveguide and lens extends in anoptical path substantially in the first direction.
 11. The apparatus ofclaim 10 further including a top cladding layer formed on the waveguide.12. The apparatus of claim 11 wherein the top cladding layer is furtherformed on a top surface of the lens structure.
 13. The apparatus ofclaim 10, wherein the optical lens has an inclined top surface that isarranged at an angle to the bottom cladding layer.
 14. The apparatus ofclaim 10, wherein the bottom cladding layer is formed on a substrate.15. The apparatus of claim 10, wherein the apparatus is formed on asubstrate that comprises the bottom cladding layer.
 16. The apparatus ofclaim 10, wherein an optical face of the lens is configured such thatlight rays transmitted from the waveguide are collimated by the lens sothat the light rays are emitted through the lens are projected in aplane that is substantially coplanar to the top surface of the bottomcladding layer.
 17. The apparatus of claim 10, wherein the optical lenshas a directionally collimating lens curve that has an outline that issubstantially defined within at least a plane that is coplanar with thetop surface of the bottom cladding layer, wherein the light raystransmitted from the waveguide are collimated such that substantiallyall of the light rays emitted though the directionally collimating lenscurve are parallel to each other and travel in a single direction. 18.The apparatus of claim 10, wherein the bottom cladding material isplanar in construction.